Interpretive Summary: Peanut meal is an excellent source of protein but the typically high levels of aflatoxin associated with this material current limit its applications to relatively low value feed or fertilizer applications. This work evaluated the potential of an inexpensive sodium bentonite additive to sequester aflatoxin from contaminated (~110 ppb) peanut meal during protein extraction. The additive was added to aqueous dispersions of peanut meal and was effective at sequestering aflatoxin such that detectable levels of the toxin were below 20 ppb in both the water soluble, high protein extracts and also the water insoluble portions of these dispersions. This sequestering capacity was effective at pH 2.0 and pH 8.0 both in the presence and absence of pepsin and Alcalase, respectively, which are two commercially available proteases that were shown to improve extraction efficiency. This work demonstrates a key proof of principle necessary to convert aflatoxin contaminated peanut meal into the following value added components: 1) protein/peptide concentrates that are aflatoxin free and appropriate for high value feed, and eventually food, applications and 2) insoluble solids containing the sequestered aflatoxin which is appropriate for high value feed applications as the aflatoxin is biologically unavailable.

Technical Abstract:
The efficacy of a bentonite clay, Astra-Ben 20A (AB20A), to sequester aflatoxin from contaminated (~110 ppb) peanut meal during protein extraction was studied. Aqueous peanut meal dispersions (10% w/w) were prepared varying pH, temperature, enzymatic hydrolysis conditions, and concentrations of AB20A. After extraction, dispersions were centrifuged and filtered to separate both the water-soluble and water-insoluble fractions for subsequent testing. Inclusion of AB20A at 0.2 and 2% reduced (p<0.05) aflatoxin concentrations below 20 ppb in both fractions; however, the higher concentration of AB20A also reduced (p<0.05) water soluble protein content. Inclusion of 0.2% AB20A did not affect protein solubility, total soluble solids, or degree of hydrolysis. Peanut meal adsorption isotherms measured AB20A capacity to sequester aflatoxin. These results are discussed in the context of a process designed to sequester aflatoxin from contaminated peanut meal, which could enable derivatives of this high protein material to be utilized in enhanced feed and/or food applications.